1. Field of the Invention
The present invention is broadly concerned with a high-capacity patty forming apparatus adapted for use in the commercial production of meat patties formed of, for example, chicken, beef, or pork. More particularly, it is concerned with equipment of this type which preferably is equipped with a cavity head adapted to receive and form patties, and a piston having a segmented, non-porous patty-engaging face together with structure for delivering bursts of pressurized air through the piston face in order to positively disengage the formed patties from the cavity. The preferred apparatus includes a three-member, segmented piston face plate assembly provided with air passageways formed between the members and adapted to be easily disassembled for cleaning.
2. Description of the Prior Art
Large food processors supplying meat patties to restaurants and fast food chains make use of industrial sized patty forming equipment. Such equipment is essential in order to economically produce the huge quantities of meat patties needed to meet consumer demand. In general, this equipment includes at least one piston and cavity head adapted to move between a retracted meat-filling position, wherein a patty forming cavity is filled with meat, to an extended patty-discharging position.
U.S. Pat. No. 4,987,643 (incorporated by reference herein) describes a patty forming apparatus especially designed for high-capacity patty formation. To this end, the apparatus described in the '643 patent is provided with a novel reciprocating slide plate equipped with a removable, multiple piston and cavity head adapted to receive and form patties, and with a piston-adjusting mechanism permitting both individual and ganged adjustment of patty thickness without the necessity of piston removal. The pistons disclosed in the '643 patent are provided with a porous, sintered metal or ceramic face plate coupled to and defining the lowermost material-engaging face of the overall piston.
In experimental practice with the apparatus described in the '643 patent, it has been determined that the porous face plate is difficult to machine and, in use, becomes easily plugged and may be difficult to clean. The porous face plate is typically formed of sintered material having an average pore diameter of from 2 to about 15 microns (most preferably about 5 microns). The process of sintering generally involves the compression of metal powders at room temperature and the subsequent baking of the resulting compact at elevated temperatures without the application of pressure.
Because virtually any shaped piston can be used, including circular, square, oval or contoured free form, a sintered compact must be fabricated to conform to the piston shape. This forming process often requires that the sintered compact undergo difficult machining and welding processes. Machining is difficult because the compact is generally brittle and can become deformed easily during face plate fabrication. Welding is difficult because the welding and forming characteristics of a sintered metal are different than those of a welding rod of identical metal often used during face plate fabrication.
In operation, the sintered face plate can become plugged or fouled with patty material because of the small average pore diameter. Once plugged, the sintered face plate is troublesome to effectively clean and unplug. A sintered face plate which cannot be effectively cleaned must be discarded, requiring that a new face plate be installed, resulting in higher equipment and operational costs.
There is accordingly a need in the art for an improved piston apparatus having means by which pressurized air may be directed through the piston and piston face for forcibly separating a formed patty from the piston face, which is easier and less costly to manufacture; and which, in operation, undergoes less plugging and is easier to clean.